London: The simple phenomenon of a water puddle drying in the sun may have driven chemical reactions that were critical to the formation of life on early Earth, shows research.

The research team, that included an Indian-origin scientist, supports the theory that life could have begun on dry land, perhaps even in the desert, where cycles of night-time cooling and dew formation are followed by daytime heating and evaporation.

Just 20 of these day-night, wet-dry cycles were required to form a complex mixture of polypeptides - important molecules of contemporary life - in the lab.

Polypeptides were formed simply by mixing amino and hydroxy acids -- which are believed to have existed together on early Earth -- then subjecting them to the cycles of wet and dry conditions.

The potential importance of this reaction in the earliest stages of life is supported by studies of meteorites that revealed that both compounds would have been present on pre-biotic Earth.

"The demonstration of peptide formation opens the door to asking other questions about how life may have gotten going in prebiotic times," said Ramanarayanan Krishnamurthy, member of the research team and associate professor of chemistry at the Scripps Research Institute.

The process also allowed the breakdown and reassembly of the organic materials to form random sequences that could have led to the formation of the polypeptide chains that were needed for life, researchers reported in the journal Angewandte Chemie International Edition.

"The simplicity of using hydration-dehydration cycles to drive the kind of chemistry you need for life is really appealing," said Nicholas Hud, professor at Georgia Institute of Technology and director of the NSF Center for Chemical Evolution.

"It looks like dry land would have provided a very favourable environment for getting the chemistry necessary for life started," he added.

Scientists had previously made polypeptides from amino acids by heating them well past the boiling point of water. But the high temperatures are beyond the point at which most life could survive.

"The simplicity of the wet-dry cycle, therefore, makes it attractive to explain how peptides could have formed," Hud said.